1. Field of Invention
The invention relates to an engine cooling device/method designed to cool an engine through circulation of cooling medium.
2. Description of Related Art
As an engine cooling device designed to cool an engine through circulation of cooling medium, a cooling device equipped with a heat-accumulating container has been known. A cooling device of this type causes cooling medium that has reached a high temperature by receiving heat from an engine to flow into a heat-accumulating container, and thereby makes it possible to thermally insulate and store the cooling medium.
As an engine cooling device equipped with a heat-accumulating container, there is known a device that is disclosed in Japanese Patent Application No. 10-77839 as an example of the related art. This cooling device is constructed as follows.
That is, a radiator passage and a bypass passage are provided as cooling medium passages for causing cooling medium to flow. The radiator passage is designed to cause cooling medium that has flown out from a body of an engine to flow into the body of the engine via a radiator. The bypass passage is designed to cause cooling medium that has flown out from the body of the engine to flow into the body of the engine without causing the cooling medium to flow via the radiator.
The bypass passage is provided with a control valve. The flow rate of cooling medium flowing through the bypass passage can be adjusted through control of the control valve. A cooling circuit for causing cooling medium to circulate is so constructed as to include the control valve, the radiator passage, and the bypass passage.
Further, as a cooling medium passage, there is provided a heat-accumulating passage that has a heat-accumulating container and that can be selectively connected to the cooling circuit. This heat-accumulating passage is connected to the cooling circuit, whereby a heat-accumulating circuit for causing cooling medium in the heat-accumulating container to circulate via the body of the engine is constructed.
In the aforementioned engine cooling device, when the engine is started, hot cooling medium in the heat-accumulating container is caused to flow into the engine by connecting the heat-accumulating passage to the cooling circuit. If the temperature of the cooling medium in the heat-accumulating container becomes lower than a predetermined temperature, the warm-up of the engine is promoted by disconnecting the heat-accumulating passage from the cooling circuit.
Whether cooling medium in the heat-accumulating container is supplied to the engine or the heat-accumulating passage is disconnected from the cooling circuit, the bypass passage is closed to prevent low-temperature cooling medium from being recirculate to the body of the engine. Thus, the warm-up performance of the engine is further enhanced.
In causing cooling medium in the heat-accumulating container to flow into the body of the engine, if cooling medium is caused to circulate with the bypass passage closed as in the case of the aforementioned related art, the following problem may arise.
That is, the flow resistance of cooling medium is increased by closing the bypass passage. Hence, the cooling medium cannot be guaranteed to flow through the cooling circuit and the heat-accumulating circuit at a sufficient flow rate. This results in a delay in warming up the engine.